Question

3a,a,-a upto a terms find the sum of the following ap

Answer 1

Answer:

4a²-a³

Step-by-step explanation:

3a,,a,-a.....

here A=3a

d=a-3a=-2a

sum of a terms

Sa=a/2*[2*3a+(a-1)*(-2a)]

=a/2(6a-2a2+2a)

=a/2(8a-2a2)

=4a²-a³